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7 <firstname>Bdale</firstname>
8 <surname>Garbee</surname>
11 <firstname>Keith</firstname>
12 <surname>Packard</surname>
16 <holder>Bdale Garbee and Keith Packard</holder>
18 <title>TeleMetrum</title>
19 <subtitle>Owner's Manual for the TeleMetrum System</subtitle>
22 This document is released under the terms of the
23 <ulink url="http://creativecommons.org/licenses/by-sa/3.0/">
24 Creative Commons ShareAlike 3.0
31 <revnumber>0.1</revnumber>
32 <date>30 March 2010</date>
33 <revremark>Initial content</revremark>
38 <title>Introduction and Overview</title>
40 Welcome to the Altus Metrum community! Our circuits and software reflect
41 our passion for both hobby rocketry and Free Software. We hope their
42 capabilities and performance will delight you in every way, but by
43 releasing all of our hardware and software designs under open licenses,
44 we also hope to empower you to take as active a role in our collective
48 The focal point of our community is TeleMetrum, a dual deploy altimeter
49 with fully integrated GPS and radio telemetry as standard features, and
50 a "companion interface" that will support optional capabilities in the
54 Complementing TeleMetrum is TeleDongle, a USB to RF interface for
55 communicating with TeleMetrum. Combined with your choice of antenna and
56 notebook computer, TeleDongle and our associated user interface software
57 form a complete ground station capable of logging and displaying in-flight
58 telemetry, aiding rocket recovery, then processing and archiving flight
59 data for analysis and review.
63 <title>Specifications</title>
68 Recording altimeter for model rocketry.
73 Supports dual deployment (can fire 2 ejection charges).
78 70cm ham-band transceiver for telemetry downlink.
83 Barometric pressure sensor good to 45k feet MSL.
88 1-axis high-g accelerometer for motor characterization, capable of
89 +/- 50g using default part.
94 On-board, integrated GPS receiver with 5hz update rate capability.
99 On-board 1 megabyte non-volatile memory for flight data storage.
104 USB interface for battery charging, configuration, and data recovery.
109 Fully integrated support for LiPo rechargeable batteries.
114 Uses LiPo to fire e-matches, support for optional separate pyro
120 2.75 x 1 inch board designed to fit inside 29mm airframe coupler tube.
126 <title>Handling Precautions</title>
128 TeleMetrum is a sophisticated electronic device. When handled gently and
129 properly installed in an airframe, it will deliver extraordinary results.
130 However, like all electronic devices, there are some precautions you
134 The Lithium Polymer rechargeable batteries used with TeleMetrum have an
135 extraordinary power density. This is great because we can fly with
136 much less battery mass than if we used alkaline batteries or previous
137 generation rechargeable batteries... but if they are punctured
138 or their leads are allowed to short, they can and will release their
140 Thus we recommend that you take some care when handling our batteries
141 and consider giving them some extra protection in your airframe. We
142 often wrap them in suitable scraps of closed-cell packing foam before
143 strapping them down, for example.
146 The TeleMetrum barometric sensor is sensitive to sunlight. In normal
147 mounting situations, it and all of the other surface mount components
148 are "down" towards whatever the underlying mounting surface is, so
149 this is not normally a problem. Please consider this, though, when
150 designing an installation, for example, in a 29mm airframe's see-through
154 The TeleMetrum barometric sensor sampling port must be able to "breathe",
155 both by not being covered by foam or tape or other materials that might
156 directly block the hole on the top of the sensor, but also by having a
157 suitable static vent to outside air.
160 As with all other rocketry electronics, TeleMetrum must be protected
161 from exposure to corrosive motor exhaust and ejection charge gasses.
165 <title>Hardware Overview</title>
167 TeleMetrum is a 1 inch by 2.75 inch circuit board. It was designed to
168 fit inside coupler for 29mm airframe tubing, but using it in a tube that
169 small in diameter may require some creativity in mounting and wiring
170 to succeed! The default 1/4
171 wave UHF wire antenna attached to the center of the nose-cone end of
172 the board is about 7 inches long, and wiring for a power switch and
173 the e-matches for apogee and main ejection charges depart from the
174 fin can end of the board. Given all this, an ideal "simple" avionics
175 bay for TeleMetrum should have at least 10 inches of interior length.
178 A typical TeleMetrum installation using the on-board GPS antenna and
179 default wire UHF antenna involves attaching only a suitable
180 Lithium Polymer battery, a single pole switch for power on/off, and
181 two pairs of wires connecting e-matches for the apogee and main ejection
185 By default, we use the unregulated output of the LiPo battery directly
186 to fire ejection charges. This works marvelously with standard e-matches
187 from companies like [insert company and product names for e-matches we've
188 tried and like] and with Quest Q2G2 igniters. However, if you
189 want or need to use a separate pyro battery, you can do so by adding
190 a second 2mm connector to position B2 on the board and cutting the
191 thick pcb trace connecting the LiPo battery to the pyro circuit between
192 the two silk screen marks on the surface mount side of the board shown
196 We offer two choices of pyro and power switch connector, or you can
197 choose neither and solder wires directly to the board. All three choices
198 are reasonable depending on the constraints of your airframe. Our
199 favorite option when there is sufficient room above the board is to use
200 the Tyco pin header with polarization and locking. If you choose this
201 option, you crimp individual wires for the power switch and e-matches
202 into a mating connector, and installing and removing the TeleMetrum
203 board from an airframe is as easy as plugging or unplugging two
204 connectors. If the airframe will not support this much height or if
205 you want to be able to directly attach e-match leads to the board, we
206 offer a screw terminal block. This is very similar to what most other
207 altimeter vendors provide by default and so may be the most familiar
208 option. You'll need a very small straight blade screwdriver to connect
209 and disconnect the board in this case, such as you might find in a
210 jeweler's screwdriver set. Finally, you can forego both options and
211 solder wires directly to the board, which may be the best choice for
212 minimum diameter and/or minimum mass designs.
215 For most airframes, the integrated GPS antenna and wire UHF antenna are
216 a great combination. However, if you are installing in a carbon-fiber
217 electronics bay which is opaque to RF signals, you may need to use
218 off-board external antennas instead. In this case, you can order
219 TeleMetrum with an SMA connector for the UHF antenna connection, and
220 you can unplug the integrated GPS antenna and select an appropriate
221 off-board GPS antenna with cable terminating in a U.FL connector.
225 <title>Operation</title>
231 <title>Using Altus Metrum Products</title>
233 <title>Being Legal</title>
235 First off, in the US, you need an [amateur radio license](../Radio) or
236 other authorization to legally operate the radio transmitters that are part
240 <title>In the Rocket</title>
242 In the rocket itself, you just need a [TeleMetrum](../TeleMetrum) board and
243 a LiPo rechargeable battery. An 860mAh battery weighs less than a 9V
244 alkaline battery, and will run a [TeleMetrum](../TeleMetrum) for hours.
247 By default, we ship TeleMetrum with a simple wire antenna. If your
248 electronics bay or the airframe it resides within is made of carbon fiber,
249 which is opaque to RF signals, you may choose to have an SMA connector
250 installed so that you can run a coaxial cable to an antenna mounted
251 elsewhere in the rocket.
255 <title>On the Ground</title>
257 To receive the data stream from the rocket, you need an antenna and short
258 feedline connected to one of our [TeleDongle](../TeleDongle) units. The
259 TeleDongle in turn plugs directly into the USB port on a notebook
260 computer. Because TeleDongle looks like a simple serial port, your computer
261 does not require special device drivers... just plug it in.
264 Right now, all of our application software is written for Linux. However,
265 because we understand that many people run Windows or MacOS, we are working
266 on a new ground station program written in Java that should work on all
270 After the flight, you can use the RF link to extract the more detailed data
271 logged in the rocket, or you can use a mini USB cable to plug into the
272 TeleMetrum board directly. Pulling out the data without having to open up
273 the rocket is pretty cool! A USB cable is also how you charge the LiPo
274 battery, so you'll want one of those anyway... the same cable used by lots
275 of digital cameras and other modern electronic stuff will work fine.
278 If your rocket lands out of sight, you may enjoy having a hand-held GPS
279 receiver, so that you can put in a waypoint for the last reported rocket
280 position before touch-down. This makes looking for your rocket a lot like
281 Geo-Cacheing... just go to the waypoint and look around starting from there.
284 You may also enjoy having a ham radio "HT" that covers the 70cm band... you
285 can use that with your antenna to direction-find the rocket on the ground
286 the same way you can use a Walston or Beeline tracker. This can be handy
287 if the rocket is hiding in sage brush or a tree, or if the last GPS position
288 doesn't get you close enough because the rocket dropped into a canyon, or
289 the wind is blowing it across a dry lake bed, or something like that... Keith
290 and Bdale both currently own and use the Yaesu VX-7R at launches.
293 So, to recap, on the ground the hardware you'll need includes:
294 <orderedlist inheritnum='inherit' numeration='arabic'>
296 an antenna and feedline
305 optionally, a handheld GPS receiver
308 optionally, an HT or receiver covering 435 Mhz
313 The best hand-held commercial directional antennas we've found for radio
314 direction finding rockets are from
315 <ulink url="http://www.arrowantennas.com/" >
318 The 440-3 and 440-5 are both good choices for finding a
319 TeleMetrum-equipped rocket when used with a suitable 70cm HT.
323 <title>Data Analysis</title>
325 Our software makes it easy to log the data from each flight, both the
326 telemetry received over the RF link during the flight itself, and the more
327 complete data log recorded in the DataFlash memory on the TeleMetrum
328 board. Once this data is on your computer, our postflight tools make it
329 easy to quickly get to the numbers everyone wants, like apogee altitude,
330 max acceleration, and max velocity. You can also generate and view a
331 standard set of plots showing the altitude, acceleration, and
332 velocity of the rocket during flight. And you can even export a data file
333 useable with Google Maps and Google Earth for visualizing the flight path
334 in two or three dimensions!
337 Our ultimate goal is to emit a set of files for each flight that can be
338 published as a web page per flight, or just viewed on your local disk with
343 <title>Future Plans</title>
345 In the future, we intend to offer "companion boards" for the rocket that will
346 plug in to TeleMetrum to collect additional data, provide more pyro channels,
347 and so forth. A reference design for a companion board will be documented
348 soon, and will be compatible with open source Arduino programming tools.
351 We are also working on the design of a hand-held ground terminal that will
352 allow monitoring the rocket's status, collecting data during flight, and
353 logging data after flight without the need for a notebook computer on the
354 flight line. Particularly since it is so difficult to read most notebook
355 screens in direct sunlight, we think this will be a great thing to have.
358 Because all of our work is open, both the hardware designs and the software,
359 if you have some great idea for an addition to the current Altus Metrum family,
360 feel free to dive in and help! Or let us know what you'd like to see that
361 we aren't already working on, and maybe we'll get excited about it too...